Rolling head for roto-form machine

ABSTRACT

Apparatus for cold bending metal tubes involving application of pressure on a pressure roller generated by an oscillating eccentric operating directly on the pressure roller. This invention relates to improvements in machines for cold bending of metallic tubes of relatively large diameter by applying rolling pressure to the inside wall surface of the tube over a specific area located on the portion of the tube in which the other arc of curvature is generated so as to thin said wall portion by rolling pressure without appreciable alteration in the thickness of the opposite portion of the tube wall.

[72] Inventor Constantin Troyanski Cicero,lll. [2|] Appl.No. 700,071 [22] Filed Jan.24, 1968 [45] Patented Apr. 13, 1971 [73] Assignee Pines Engineering Co.,1nc.

Aurora,1ll.

[54] ROLLING HEAD FOR ROTO-FORM MACHINE 8 Claims, 8 Drawing Figs.

[52] U.S.Cl 72/113, 72/123 [51] Int.Cl B2ld 1/08 [50] FieldofSearch 72/113, 123,122

[56] References Cited UNITED STATES PATENTS 2,901,930 9/1959 Wilman 72/123 3,357,221 12/1967 Wilman 72/123X 3,029,668 4/1962 Wilman 72/123 672,448 4/1901 MacKenzie 72/123X Primary Examiner-Richard .l. Herbst Assistant Examiner-A. L. Havis Attorney-Hofgren, Wegner, Allen, Stellman & McCord ABSTRACT: Apparatus for cold bending metal tubes involving application of pressure on a pressure roller generated by an oscillating eccentric operating directly on the pressure roller.

This invention relates to improvements in machines for cold bending of metallic tubes of relatively large diameter by applying rolling pressure to the inside wall surface of the tube over a specific area located on the portion of the tube in which the other arc of curvature is generated so as to thin said wall portion by rolling pressure without appreciable alteration in the thickness of the opposite portion of the tube wall.

Patented April 13, 1971 4 Sheets-Sheet 1 INVENTOR Patented April 13, 1971 4 Sheets-Sheet 2 INVENT R CmsZa/z 2?) Wa /a/zslz.

A ORNEY AAe/WMW Patented April 13, 1971 3,575,026

4 Sheets- Sheet 5 INVENTOR ATTORNEY 13 Conga/2222 Waymska'.

Patente d. A ril-13, 1971 I 3,575,026

4 Sheets-Sheet. 4

llilGLlLllNG HEAD FOR ROT FORM| MACHINE This results in elongation of the thinned wall area to a predetermined degree so as to determine the radius of curvature generated in the tube. The degree of bending is dependent upon the depth of the rolling pressure applied. The herein disclosed structure embodies a rotating head and novel eccentric means for determining the depth of the rolling pressure, for effecting the requisite thinning operation, and for absorbing the pressure load directly by the shaft supporting the rotating head.

Heretofore, such application of pressure for thinning a wall to a predetermined amount has been effected by adjustment of a pressure roller through rotational adjustment of an eccentric shaft mounting the pressure roller, which shaft carries the entire load of the applied pressure. One such assembly is disclosed in a patent to Wilman, No. 3,029,668, issued Apr. 17, 1962. Such load carrying pressure roller lacks means to insure absolute uniformity in the thinning of the tube wall due to the nature of its construction and assembly.

In the herein disclosed structure, the pressure roller is carried in a semifloating yoke mounted in the rotatable head and said roller is backed by an eccentric-mounted roller carried on the support shaft. The assembly and relationship of the parts is such that the eccentric roller absorbs the pressure load thus relieving the pressure roller bearings of undue wear. Also, said eccentric roller functions to locate the pressure roller for generation of a thin wall of predetermined precise unifonn thickness in the tube being worked.

More specifically, the present structure embodies a shaft having an eccentric portion on which is mounted a roller having direct engagement with the circumferential surface of a semifloating pressure roller, carried in a tool head rotatable relative to said shaft. The tool head also includes, preferably two backup rollers located on the side of the tool head remote from the side carrying the pressure roller and spaced axially rearwardly from the pressure roller. In use the eccentric and its mounting shaft are oscillated during rotation of the tool head, to move the pressure roller toward and away from the tube wall for thinning the wall of the tube in the area of the outside arc of the bend being performed therein a predetermined amount. As the tool head rotates, the pressure roller is repeatedly pressed by the eccentric roller against the requisite area of the tube wall thus thinning the wall area with a high degree of accuracy and the oscillation of the eccentric roller and its mounting shaft varies the load on the pressure roller.

It is, therefore, an object of the invention to provide a tube bending apparatus of novel construction.

Another object is to provide, in tube bending apparatus, a pressure roller and a novel backup eccentric roller carried in the tool head.

Another object is to provide a tube bending apparatus of the character referred to with novel means to vary the load on the pressure roller to vary the amount of thinning to be accomplished on the wall of a tube.

Another object is to provide a tool head of a tube bending apparatus with novel mounting means for the pressure roller. Another object is to provide novelmeans to relieve the bearings of a pressure roller from the applied load and thus maintain uniformity in the tube bending operation, and insure long wearing life to the apparatus.

Another object is to provide apparatus of the character referred to which is not prohibitively-- expensive to manufacture or expensive or difficult to maintain in serviceable condition, and one that is very accurate in use, simple to operate and to adjust, and highly efficient in use.

The structure by means of which the above noted and other advantages and objects of the invention are attained will be described in the following specification, taken in conjunction with the accompanying drawings, showing a preferred illustrative embodiment of the invention, in which;

F HO. 1 is a longitudinal axial section view of a tube portion during the bending thereof by means of the tool head assembly of this invention;

FIG. 2 is a transverse sectional view taken substantially on line 2-2 of FIG. ll;

FIG. 3 is a perspective view of the backup roller shaft;

FIG. 6 is a plan view of the rotatable head, showing the pressure roller mounting yoke;

FIG. 5 is a transverse sectional view taken substantially on line 5-5 of FIG. 1;

FIGS. 6 and 7 are, respectively, end and sectional views of a representative structure for effecting oscillation of the eccentric shaft during its rotation; and

FIG. 5 is a schematic view illustrating a start position of the roller head and eccentric.

Referring to the exemplary disclosure of the invention as shown in the accompanying drawings, and particularly to FIG. I, the apparatus includes a rotatable tool head 11 which is substantially cylindrical in section and which is mounted, in a manner to be more fully described hereinafter, on a shaft 12. The shaft 12 is mounted to have oscillatable rotation with respect to the head 11 for purposes of varying the load pressure applied thereby to a pressure roller 13 carried by said head. Preferably, the shaft 12 has an axial oil passage 12c in communication with radial ports for delivering oil to all bearings so that dirt, etc. is washed outwardly to keep the bearings clean, and the assembly is kept cool.

Specifically, the head 11 is journaled for free rotation relative to shaft 112, said shaft having bearing surfaces 12a and 12b receiving thereover roller bearings l4 seated in internal bearing surfaces 15, one formed in the head and the other in a front bearing cap 16 secured to the head as by bolts 17. The shaft bearing surfaces 12a and 12b are arranged one on each side of an eccentric shaft portion 18 on which is journaled for free rotation an eccentric roller 19'. Bearing 21 is interposed between roller 19 and shaft portion 18 and an axial thrust bearing 22 is located on one side of the roller 19 whereas a thrust washer 23 or a thrust bearing is located on the other side thereof.

As will be explained presently, the pressure roller 13 is mounted in the head in such a manner as to be movable inwardly and outwardly radially for purposes of having working engagement with the inner surface of a length of tubular stock 5". Said roller is carried in a yoke 2d that is seated in a cutout 25 (FIG. 2) in the wall of head It and is journaled along one edge by a pin 26 mounted at its ends in said wall. The other or free edge of said yoke carries an eyebolt 27 (FIG. 5) that projects through a bore 25 in said head wall. The bore is enlarged at 29 and a spring 31 is fitted over the bolt within said enlargement 25 and secured to said bolt by a nut 32. It will thus be seen that the spring 31 normally holds the yoke and its pressure roller 13 retracted into the head and maintains the pressure roller in circumferential surface contact at all times with eccentric roller l9. Thus, when shaft 12 is rotatably oscillated to alter the radial position of its eccentric portion It the eccentric roller 19 will intermittently engage and urge the pressure roller 13 outwardly radially or permit it to be retracted. Angular oscillation of shaft 12 with respect to rotating head ill is accomplished by the oscillation means illustrated in FIGS. 6 and '7 connected through shaft extension 33 with shaft l2 and through shaft extension 52 with head Ill. The oscillation means of FIGS. 6 and '7 permit the adjustment of the amplitude of oscillation of shaft extension 33.

A cylindrical case 55 supports, through its center, shaft extension 33 which has a crank 56 fixedly connected thereto. A pivot pin 57 at the end of rank 56 connects an extensible link 56 thereto, the length of which can be changed by adjustment nut 59. Roller 3d at the end of link 58 rides on the surface 35 of a movable cam 60. Roller 34 and the end of link 58 are connected through a pivot pin 62 with a link '70 which is in turn connected through pivot pin 64 with crank 65 mounted on shaft extension 52.

As shaft extension 52 turns with head 11, crank 65 turns and roller 34 follows the inner surface of cam 60. When the roller traverses the portion 35 of the cam surface, the angular relation of the cranks 56, 65 and links 55, 63 changes, causing an angular oscillation of shaft extension 33 with respect to shaft extension 52. Thus, the eccentric portion 18 of shaft 12 and eccentric roller 19 cause the desired radial movement of pressure roller 13.

The cyclical depth to which the pressure roller is advanced, and thus the bend radius, is controlled by the position of cam 60. in the extreme left cam portion of FIG. 7, shaft 12 has maximum oscillation and a minimum bend radius is achieved. Movement of the cam to the right reduces oscillation and increases the bend radius. The cam 60 may be moved by means of a hand wheel 68 and screw 69 threaded into case 55. The radius of curvature of the tube may be changed during operation of the bending machine.

As noted hereinbefore, the pressure roller 13 is carried by yoke 24. As best shown in FIG. 4, the yoke is fabricated of two pieces held together rigidly by bolts 36 and forming between them a rectangular recess 37 in which the pressure roller 13 is arranged. The pressure roller 13 is carried firmly on a shaft 38 that has its ends journaled in radial bearings 38a one in each yoke section. Suitable thrust bearings 39 afford antifriction bearings for the roller mount.

The head 11 also has longitudinal recesses 41 formed in its wall opposed to the side carrying the yoke 24. As shown best in FIG. 2, there are two such recesses, one located about 45 on each side of the diametrical center from the pressure roller 13. These recesses each contain a backup roller 42 each mounted for free rotation on a shaft 43 (FIG. 3) that has squared or flattened ends 430 and 43 b which nest in the head recesses and are secured to the head as by bolts 44. Preferably, roller bearings 45 are interposed between each backup roller and its shaft, and axial thrust bearings 46 are disposed on the forward face of each roller, with a thrust washer or bearing 47 bearing against the opposed roller end. These two backup rollers 42 are intended to bear at all times, during a bending operation, against the inside wall of the tube S. It should be noted at this time that the backup rollers 42 lie in a plane to the rear of the plane of the pressure roller 13 so as to ride free and clear of any build up of excess displaced tube material immediately to the rear of the pressure roller. Such a build up is illustrated at 48 in HO. 1.

The head 11 extends rearwardly for some distance from the backup rollers 42 and, as shown, its rearmost end is telescoped over a bushing 49 secured firmly in the shaft extension 33. The rear end of the head extension has bolted to it, as by bolts 51, a tubular shaft extension 52 that extends some distance rear wardly thereof and which is operably connected to power means (not shown) for rotating the head and shaft extension at a high rate of speed during machine operation.

When the apparatus is initially set up with a tube S disposed thereover, the head is positioned so that the pressure roller is at the upper side of the tube. This is illustrated in FIG. 8. AT this time the eccentric roller 19 is in a selected retracted position relative to the pressure roller. The shaft 12 is rotated to cause the pressure roller to touch the inside surface of the tube wall. This is the start position. in bending the tube, as the tube is advanced over the head, the conical member 35 is moved, as to the left in FIG. 7, and stopped in the position corresponding to the desired radius of curvature by which the tube is to be bent. Both the shaft extension 33 and head extension shaft 52 will rotate together but, at intervals during such rotation, the shaft extension and, thus, the shaft 12 will be oscillated because of their operative association with the conical surface 35. This oscillation progressively increases as the pressure roller advances around the inside of the tube to increase the rolling depth of the pressure roller 13 until it reaches its maximum position whereupon its rolling depth will then decrease as it approaches the start position. The tube area of progressive increase and progressive decrease of the rolling depth of the pressure roller will be thinned to the desired thickness so as to create the outer arc of the bent tube.

Although I have described a preferred embodiment of the invention in considerable detail, it will be understood that the description thereof is intended to be illustrative, rather than restrictive, as details of the structure ma be modified or changed without departing from the spin or scope of the invention. Accordingly, l do not desire to be restricted to the exact construction described.

lclaim:

1. in a device for bending tubes, having a first rotating shaft and a second rotating shaft with means for angularly oscillating said second shaft with respect to the first, an improved bending apparatus comprising a head connected with said first shaft for rotation inside a tube to be bent:

at pressure roller rotatably mounted on said head and projecting radially from roller side thereof and having a longitudinal axis; at least two backup rollers rotatably mounted in said head and extending radially from another side of the head and having longitudinal axes, said pressure roller and said backup rollers being positioned on the head for bearing against opposite portions of the inner surface of said tube;

an eccentric shaft carried in said head and connected with said second rotating shaft; and

a roller on said eccentric shaft having surface contact with the surface of the pressure roller at all times, said eccentric shaft roller being operable upon oscillation of said second shaft to increase and decrease the distance between the axes of the pressure roller and the backup rollers at each revolution of the head so as to generate the outer arc of curvature of said tube.

2. The device recited in claim 1, in which the pressure roller is joumaled in a yoke pivotally mounted in the head so as to lie normally substantially within the perimeter of said head.

3. The device recited in claim 2, in which spring means is provided to urge the yoke about its pivotal mounting to a retracted position into the head.

4. The device recited in claim 1, in which the pressure roller is mounted for free rotation in a yoke pivotally mounted on and normally retracted into the head, and the eccentricmounted roller operates to move the yoke and pressure roller bodily away from the axis of said head.

5. The device recited in claim 4, in which spring means is provided to return the yoke and pressure roller to their retracted positions.

6. The device recited in claim 1, in which an eccentric is carried on said shaft and the rotatable head is axially journaled on said shaft.

7. The device recited in claim I, in which the eccentric mounted roller is carried on an axial shaft so that external pressure on the pressure roller is transmitted directly to said shaft.

8. The device recited in claim 1, in which radial bearings absorb the load pressure on the eccentric roller. 

1. In a device for bending tubes, having a first rotating shaft and a second rotating shaft with means for angularly oscillating said second shaft with respect to the first, an improved bending apparatus comprising a head connected with said first shaft for rotation inside a tube to be bent: a pressure roller rotatably mounted on said head and projecting radially from roller side thereof and having a longitudinal axis; at least two backup rollers rotatably mounted in said head and extending radially from another side of the head and having longitudinal axes, said pressure roller and said backup rollers being positioned on the head for bearing against opposite portions of the inner surface of said tube; an eccentric shaft carried in said head and connected with said second rotating shaft; and a roller on said eccentric shaft having surface contact with the surface of the pressure roller at all times, said eccentric shaft roller being operable upon oscillation of said second shaft to increase and decrease the distance between the axes of the pressure roller and the backup rollers at each revolution of the head so as to generate the outer arc of curvature of said tube.
 2. The device recited in claim 1, in which the pressure roller is journaled in a yoke pivotally mounted in the head so as to lie normally substantially within the perimeter of said head.
 3. The device recited in claim 2, in which spring means is provided to urge the yoke about its pivotal mounting to a retracted position into the head.
 4. The device recited in claim 1, in which the pressure roller is mounted for free rotation in a yoke pivotally mounted on and normally retracted into the head, and the eccentric-mounted roller operates to move the yoke and pressure roller bodily away from the axis of said head.
 5. The device recited in claim 4, in which spring means is provided to return the yoke and pressure roller to their retracted positions.
 6. The device recited in claim 1, in which an eccentric is carried on said shaft and the rotatable head is axially journaled on said shaft.
 7. The device recited in claim 1, in which the eccentric mounted roller is carried on an axial shaft so that external pressure on the pressure roller is transmitted directly to said shaft.
 8. The device recited in claim 1, in which radial bearings absorb the load pressure on the eccentric roller. 